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Fig. 2 | Respiratory Research

Fig. 2

From: Computational modeling of airway instability and collapse in tracheomalacia

Fig. 2

Plots of exhalation to undeformed lumen area ratio for tracheal models of 6, 8 and 10 mm diameter with varying degrees of malacic length (0 to 20 mm) and severity (cartilage/fibrous tissue properties reduced to fibrous tissue - “soft” or mucosa tissue properties -“mucosa”. a 6 mm diameter soft malacic. b 8 mm diameter soft malacic. c 10 mm diameter soft malacic. d 6 mm diameter mucosa malacic. e 8 mm diameter mucosa malacic. f 10 mm diameter soft mucosa malacic. Note that in many cases there is a nearly linear decrease in tracheal area with increasing pressure/airway force. However, in some severe malacic cases (indicated by dotted or dashed circles) there is a sharp decrease in tracheal area for little increase in airway pressure/force indicating a “snap through” instability. Lower boxes show conversion between airway force in Newtons and applied exhalation pressure, which varies due to different areas of the 6, 8 and 10 mm diameter models. Finally, cases denoted by * add such severe nonlinear instabilities that the numerical model would not converge to a solution

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